munsch



H. MUNSCH LOUD SPEAKER Jan. 27, 1931.

Filed Oct. 22, 1928 2 Sheets-Sheet l Jan. 27, 1931. H WNS@ 1,790,431

LOUD SPEAKER Filed Oct. 22. 1928 2 Sheets-Sheet 2 @7M/uch Patented Jan. 27, 1931 UNITED STATES PATE'NT OFFICE HANS Munson, or KLEIN-GLIENICKE, NEAR romsDAM, GERMANY, AssrGnon 'ro '11H31 FIRM: IDEAL WERKE AKTIENGESELLSCHAFT FR DRAHTLQSE TELEPHONIE, on

BERLIN, GERMANY LOUD-SPEAKER f Application led ctober 22, 1928, Serial No. 314,185, and in Germany April 4, 1928.,V

This invention relates to loud speakersof the kind having an armature which floats, as in the known telegraph relays, in a magnetically neutral position between two pairs of magnetic poles and which oscillates around a central pivot, under the influence of the speech currents. In such loudspeakers it has not hitherto been possible easily to adjust the position of the armaturebetween the magnetic poles by means of an adjusting screw during the operation. rlhis problem is solved by the present invention with comparatively simple means.

Figures 1-5 of the accompanying drawings illustrate the means for the adjustment of the armature between the ends of the pole shoes of the magnet.

Fig. l is a side elevation, Y

Fig. 2 is a plan view, whilst Figs. 3, 4 and 5 illustrate the device in section. Y

For the sake of clearness, the steel magnet and its pole shoes, as well as the coils, in the middle hollow space of which the armature oscillates, have not been Vshown in Figs. l-.'

Fig. 6 shows the pole shoes provided on the end surfaces of the twoflimbs of the Us shaped magnet in conjunction withthecoils but the armature adjusting means shown in 1 5 are not indicated therein;

Fig. 7 illustrates the arrangement shown in Fig. 6 with the armature adjusting means shown in Figs. 1-5 screwed on to the pole shoes.

Figs. 8 and 9 show in two diiferentelevations the armature adjusting device accordn ing to Figs. lw assembled together with the steel magnets, the pole shoes and the coils.V

As can be seen from Figs. 1-5,thearma ture a is carried by a thin, flat lspring b through the middle ofwhich it passes and to which it is soldered;` The pinV s for the diaphragm of the loud speakerV is secured to one of the ends of the armature a. The flat spring allows the armature a` to oscillate between the end surfaces of the pole shoes 79 secured to the ends of the limbs of the magnet y. (Figs. 6, 7, S, 9). The directions in which the oscillations take place are indicated by small arrows in Fig. 4. r

As will be seen from Figs. 6 and 7, the

a massive' piece of brass having-ak number' of incisions c; The supportit'sel-t is secured by means of two screws d (Fig. 3) to a framelike base-plate g, Apreferably"made by diecastingY andV which is formedv with an Aupward gate-like projection t. The latter projection serves for securing the-pole shoes p to. the

ends ofthe limbs ofthe steel magnet y, asV

can beV clearlyy seen in Figs. 7 and. 8:.'

The base-plate g abuts, as can be'y seen from i l Figs. Sfand 9, against the sideV surfaces!` of the 'limbs of the magnet y and by means of a ycounter-plate g lying against theiopposite side of the magnet as `well' as by means yof longv screws e engaging-in the Ybase-plate g, the: latter'is firmly pressedagainst the steel magnet' and is thereby secured. in a'fxedrposition Vto the magnet. V f Y The centralpart of the supporto (see Figs. 1-5) can resiliently rock around the points :2a-x owing toxits incisions k. The

vrotary a-Xis thus formed is in alignment with the. rotary'aXis-of the armature. When `the support is turned around its axis, the armament. This turning movement, and thus the adjustment of the armature, is effected by the adj ustingscrew h (Figs. 4,7, 8) which,when

turned to the right causes the support c to be pulled to the right against the pressure of the spring f. The spring is supported against the metal V,plate 'whichis secured in 4a recess provided in the base-plate g. For the sake of clearness, the metal piece c' is not shown in Fig. 1 but is indicated in Fig.

4. In order to limit the rotation of the ad- 100" V ture whichy supports is taken along there- Y with, whereby it receives the desired adjustjusting screw /L and consequently the adjustment of the armature, the former is provided with a pin m (Fig. 4) projecting on two sides, which pin abuts against the pin n provided on the metal piece z', thereby limiting the rotation of the adjusting screw to an angle of less than It is also possible to render the construction ot the support c carrying the armature mounting Zi from a metal casting, for instance, die-casting'. which is not extensible or is only Very little extensible, without the elastic rotation of the support being in any way affected at the weakened points m, around which it is intended to be elastically rotatable.

According to the invention, this is attained by this that suitabl);7 formed small plates or pieces of elastic metal. such as phosphor bronze, brass or the likel are inserted in the mould servingr for the casting of the support c at the points where the weakenings in question are to be produced` which plates. during the casting or skirtin;y ot the metal into the mould` become firmly united therewith at the points where the metal comes into Contact therewith` so that the completely cast support has weakened points which allow it to bend in the extension of the armature spring without there being any danger of breakage. i y

In this Way it is possible to simplify the manufacture of the support and at the same time cheapen the same.

-VVl1at I claim is 1. A loud speaker having a magnetically neutral armature capable of turning around its central axis, a spring on which the said armature is mounted, a support to which the said springy is attached, the said support being capable of elastically turning around an axis which is in alinement with the central axis of the armature, and an adjusting' screw for the said support, for the purpose of allowing the armature to be adjusted between the magnetic poles.

2. A loud speaker as claimed in claim 1, and in which the support consists of a sing'le piece of metal weakened by incisions therein to such an extent that the said piece of metal is capable of slightly elastically turning` around the' incisions.

In testimony whereof I affix Inv signature.

HANS Munson. 

